In the field of displaying, organic light emitting diode (OLED) devices have a bright future. However, OLED devices are very sensitive to water vapor and oxygen. Water vapor and oxygen, if penetrating into the OLED devices, may chemically react with organic materials, which may result in failure of the OLED devices. For example, when an OLED is in an operation state, if water vapor penetrates into the device, there may form a micro electrolytic cell within the device and an electrochemical reaction may occur. The resulting reaction gas may separate the metal cathode from the organic functional layer, thereby leading to device failure. Thus, water vapor and oxygen that penetrate into a OLED device are main factors that affect a service life of the OLED device.